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  • 1
    Electronic Resource
    Electronic Resource
    Ab initio calculation of molecular field interactions in rare-earth transition-metal intermetallics (invited) : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5972-5976 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The interaction, KRM, between the rare-earth 4f moment and the transition-metal 3d moments in rare-earth transition-metal intermetallics is shown to depend upon the R-5d moment, which is due to 3d–5d hybridization, and local 4f–5d exchange integrals. Both the R-5d moment and KRM may be calculated ab initio from the local spin-density approximation to density functional theory in self-consistent energy-band calculations with the localized 4f-moments fixed at their Russel–Saunders values. Detailed examples are given for the RFe2 (R=Gd−Yb) series. The exchange integrals are similar to those entering into the density functional version of Stoner theory and their energy dependence must be treated carefully. The calculated local exchange integrals are shown to be related to the molecular fields derived from spin Hamiltonians, hence to the spin-wave spectra. Reasonable agreement with values of the molecular fields extracted from inelastic neutron scattering and high field susceptibility measurements is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350092
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  • 2
    Electronic Resource
    Electronic Resource
    Calculated ground-state properties of ternary uranium compounds : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6580-6582 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The compounds UTAl (T=Fe,Co,Ni,Ru,Rh,Ir,Pt) crystallize in the hexagonal ZrNiAl structure. Measurements suggest that the 5f electrons in these compounds are itinerant [V. Sechovsky and L. Havela, in Ferromagnetic Materials, edited by E. P. Wohlfarth and K. H. J. Buschow (North-Holland, Amsterdam, 1988), Vol. 4, p. 309]. From self-consistent linear muffin-tin orbital energy-band calculations for the compounds the transition to magnetism across the series is explained in terms of the calculated Stoner products. Inclusion of spin-orbit interaction leads to an induced orbital moment in URhAl, consistent with the experimental observation that the magnetic properties of these compounds are highly anisotropic [V. Sechovsky and L. Havela, in Ferromagnetic Materials, edited by E. P. Wohlfarth and K. H. J. Buschow (North-Holland, Amsterdam, 1988), Vol. 4, p. 309].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349863
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  • 3
    Electronic Resource
    Electronic Resource
    Metamagnetism of RCo2 compounds : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6583-6585 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Self-consistent spin-polarized energy-band calculations are reported for the RCo2 compounds (R=Tb–Yb). By changing the magnitude of the 4f spin in GdCo2 from zero to seven and back to zero, hysteresis was obtained with both low- and high-moment conduction-electron states being obtained for spin less than 4. For the real compounds, when the calculations were started with no moment on the Co, low-conduction-electron moments were obtained for DyCo2–YbCo2. However, when the calculations were started with large moments on the Co the total conduction-electron moments were calculated to be 1.75 μB/f.u. for all of the compounds. It is suggested that the conduction-electron-state densities in all of the compounds are similar to those in YCo2 and LuCo2 and that the conduction-band system is essentially metamagnetic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349864
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  • 4
    Electronic Resource
    Electronic Resource
    Calculated spin and orbital moments in UNi2 : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6586-6587 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the hexagonal ferromagnet UNi2, an unusual 5f form factor for uranium has been observed, indicating a large orbital contribution to the total moment. We report on self-consistent electronic structure calculations for the hexagonal Laves phase (C14) compound UNi2, taking both spin and orbital contributions to the total moment into account. In a constrained calculation, where the spin moment is chosen to agree with experiment, very good agreement with the experimental form factor is obtained. In the analysis of the form factor both the 6d and the 5f electrons are taken into account giving improved agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349865
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetism of RFe2 compounds : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5683-5684 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The combination of itinerant transition metal (M=Fe) and localized rare earth (R=Gd-Yb) magnetism in RFe2 compounds has been investigated in self-consistent energy band calculations. The computed and measured total moments are in good agreement. We find, however, that there is a significant contribution to the moment from the R-5d partial moments coupled antiparallel to the Fe-3d moment which results from 3d-5d hybridization. The R-4f moments interact with the conduction band system solely by local exchange interactions which are calculated ab initio from density functional theory. A sum rule for the total 3d+5d moment is shown to be obeyed and an expression for the effective ferrimagnetic exchange interaction between 3d and 4f electrons is derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347937
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  • 6
    Electronic Resource
    Electronic Resource
    Implications of human papillomavirus type for survival in cervical squamous cell carcinoma (1995)
    Suite 500, 5th Floor, 238 Main Street, Cambridge, Massachusetts 02142, USA : Blackwell Science Inc.
    International journal of gynecological cancer 5 (1995), S. 0 
    Details
    ISSN: 1525-1438
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a Swedish series of 107 invasive squamous carcinomas of the cervix, DNA extraction from paraffin-embedded material was successful in 97 cases. The prevalence of human papillomavirus (HPV) in this material was 86.6%, as determined by polymerase chain reaction (PCR) using both consensus and type-specific primers. HPV type 16 was most common (42.3%; other types were 31 (12.3%), 18 (9.3%) and 33 (10.3%). Seventeen cases (17.3%) were positive for the consensus primers only and were regarded as HPV of unknown type. There was no significant difference in corrected survival between patients with HPV-positive or -negative tumors. In the HPV-positive group, patients with tumors containing HPV 33 or HPV 18 had a significantly poorer prognosis than patients with tumors containing other types of HPV DNA (relative hazard 3.18, 95% confidence interval 1.37–7.39, P = 0.007), implying a prognostic significance of HPV type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1525-1438.1995.05050341.x
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  • 7
    Electronic Resource
    Electronic Resource
    On the γ-like surface of α-Ce: Theory (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5837-5837 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have shown theoretically, by means of a full-potential LMTO method in a slab geometry, that the topmost surface layer of α-Ce is γ-like. The calculations are fully relativistic and include all electrons. Also an orbital correction to the f-electron states is included to allow for f localization. For the topmost layer the spin moment is found to be 0.70 μB for the f electrons and 0.08 μB for the d-electron states while the orbital moment from the f electrons is found to be −1.07 μB. These moments correspond well to the moments calculated for bulk γ-Ce which are 0.63, 0.07, and −0.87 μB, respectively. The subsurface and lower lying layers are calculated to have spin and orbital moments close to zero. We therefore conclude that the topmost layer on the α-Ce surface is γ-like while the subsurface and lower lying layers are similar to bulk α-Ce. Our findings explain recent photoemission experiments on this material and provide a theoretical foundation for the interpretation of these experiments. The fact that our theory assumes that α-Ce has delocalized f electrons, and the agreement with the interpretation of photoemission experiments, gives support that the Mott transition model for the α→γ phase transition is correct. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362203
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  • 8
    Electronic Resource
    Electronic Resource
    Enhancement of orbital magnetism at surfaces: Co on Cu(100) (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4983-4983 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By combining MCXD experiments with first principles electronic structure calculations, we demonstrate that the orbital contribution to magnetism can be strongly enhanced at surfaces. This effect is illustrated for Co grown on a Cu(100) surface. The MCXD measurements were performed using the SX 700 plane grating monochromators at BESSY. The Co films were evaporated and characterized in situ, for their cleanness, thickness (1.6–50 ML), and structural order. For a film thickness up to 2.2 ML, measurements of the ac MCXD susceptibility response at a fixed photon energy allowed one to measure the critical temperature, Tc, of the films and their critical properties were characterized in situ. For several samples the MCXD response as a function of the x-ray incidence angle was investigated as well. This allows one to quantify and correct saturation effects that can occur in the measurements. Data were taken in a temperature range between 40 and 350 K, and for many samples measurements were performed at several reduced temperatures, T/Tc. The first layer of Co on the Cu(100) surface shows an enhanced orbital moment, in contrast to the subsequent layers where the orbital moment is bulklike. The lowering of the symmetry, the enhanced spin moment, and the increased value of the density of states at the Fermi level are factors that combine to give the observed enhancements. © 1996 American Institute of Physics. [S0021-8979(96)679608-0]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361611
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  • 9
    Electronic Resource
    Electronic Resource
    On the semiconducting state and structural properties of YH3 from first principles theory (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3498-3500 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: With the use of first principles theory we confirm the semiconducting ground state of the technologically interesting YH3 compound. Thus, unlike previously published theories, we demonstrate that density functional theory in the local density approximation reproduces the existence of a band gap. We also show that the HoD3 structure is the stable structure at ambient conditions, in agreement with experiment. In addition, we predict that moderate applied pressure will drive YH3 into the cubic structure. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120371
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  • 10
    Electronic Resource
    Electronic Resource
    Ar incorporation in epitaxial TiN films deposited by reactive magnetron sputtering in mixed Ar/N2 discharges (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1175-1177 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: TiN films were grown on (100), (110), and (111) oriented MgO by reactive magnetron sputtering from a Ti target in mixed Ar/N2 discharges. During film growth at substrate temperatures Ts ranging from 450 to 900 °C, an applied negative substrate bias Vs (0≤Vs≤600 V) was used to vary the flux and energy of impinging Ar+ and N+2 ions. Electron channeling and transmission electron microscopy were used to show that films grown at Ts≥550 °C were epitaxial with a defect density that decreased with increasing Ts. At a constant Ts=700 °C, the films were found to remain epitaxial as Vs was increased from 0 to 200 V, but the crystalline quality clearly deteriorated with Vs=400 V and at Vs=600 V the films were polycrystalline. Energy dispersive x-ray analysis showed that the trapped Ar concentration CAr in the films was a function of both Vs and Ts. For Ts=700 °C, CAr increased with increasing Vs to reach a maximum CmaxAr at 400 V before decreasing again. The relative value of CmaxAr varied with orientation in the following manner: (110)〉(100)〉(111). At a constant Vs=400 V, CmaxAr for (110) oriented films occurred at Ts≈750 °C. These results are explained based upon ion channeling efficiency as a function of film orientation and defect structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100014
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